xref: /dragonfly/sys/vm/swap_pager.h (revision 1de703da)
1 /*
2  * Copyright (c) 1990 University of Utah.
3  * Copyright (c) 1991 The Regents of the University of California.
4  * All rights reserved.
5  *
6  * This code is derived from software contributed to Berkeley by
7  * the Systems Programming Group of the University of Utah Computer
8  * Science Department.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the University of
21  *	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  *
38  *	from: @(#)swap_pager.h	7.1 (Berkeley) 12/5/90
39  * $FreeBSD: src/sys/vm/swap_pager.h,v 1.28.2.1 2000/10/13 07:13:23 dillon Exp $
40  * $DragonFly: src/sys/vm/swap_pager.h,v 1.2 2003/06/17 04:29:00 dillon Exp $
41  */
42 
43 /*
44  * Modifications to the block allocation data structure by John S. Dyson
45  * 18 Dec 93.
46  */
47 
48 #ifndef	_SWAP_PAGER_
49 #define	_SWAP_PAGER_	1
50 
51 /*
52  * SWB_NPAGES must be a power of 2.  It may be set to 1, 2, 4, 8, or 16
53  * pages per allocation.  We recommend you stick with the default of 8.
54  * The 16-page limit is due to the radix code (kern/subr_blist.c).
55  */
56 #if !defined(SWB_NPAGES)
57 #define SWB_NPAGES 8
58 #endif
59 
60 /*
61  * Piecemeal swap metadata structure.  Swap is stored in a radix tree.
62  *
63  * If SWB_NPAGES is 8 and sizeof(char *) == sizeof(daddr_t), our radix
64  * is basically 8.  Assuming PAGE_SIZE == 4096, one tree level represents
65  * 32K worth of data, two levels represent 256K, three levels represent
66  * 2 MBytes.   This is acceptable.
67  *
68  * Overall memory utilization is about the same as the old swap structure.
69  */
70 
71 #define SWCORRECT(n) (sizeof(void *) * (n) / sizeof(daddr_t))
72 
73 #define SWAP_META_PAGES		(SWB_NPAGES * 2)
74 #define SWAP_META_MASK		(SWAP_META_PAGES - 1)
75 
76 struct swblock {
77 	struct swblock	*swb_hnext;
78 	vm_object_t	swb_object;
79 	vm_pindex_t	swb_index;
80 	int		swb_count;
81 	daddr_t		swb_pages[SWAP_META_PAGES];
82 };
83 
84 #ifdef _KERNEL
85 extern struct pagerlst swap_pager_un_object_list;
86 extern int swap_pager_full;
87 extern struct blist *swapblist;
88 
89 void swap_pager_putpages __P((vm_object_t, vm_page_t *, int, boolean_t, int *));
90 boolean_t swap_pager_haspage __P((vm_object_t object, vm_pindex_t pindex, int *before, int *after));
91 
92 int swap_pager_swp_alloc __P((vm_object_t, int));
93 void swap_pager_copy __P((vm_object_t, vm_object_t, vm_pindex_t, int));
94 void swap_pager_freespace __P((vm_object_t, vm_pindex_t, vm_size_t));
95 void swap_pager_dmzspace __P((vm_object_t, vm_pindex_t, vm_size_t));
96 void swap_pager_swap_init __P((void));
97 int swap_pager_reserve __P((vm_object_t, vm_pindex_t, vm_size_t));
98 
99 /*
100  * newswap functions
101  */
102 
103 void swap_pager_page_removed __P((vm_page_t, vm_object_t));
104 
105 /* choose underlying swap device and queue up I/O */
106 struct buf;
107 void swstrategy __P((struct buf *bp));	/* probably needs to move elsewhere */
108 
109 #endif
110 
111 #endif				/* _SWAP_PAGER_ */
112